Which of the following is a key economic indicator used in macroeconomics?

The Consumer Price Index (CPI) is a vital economic indicator in macroeconomics because it measures the average change over time in the prices paid by consumers for a basket of goods and services. The CPI reflects inflation and changes in purchasing power, which are key aspects of a nation's economic health. Policymakers, economists, and analysts use the CPI to gauge how prices are changing and to make decisions regarding monetary policy, social security adjustments, and economic forecasting.

The CPI provides insights into cost-of-living adjustments for wages and pensions. A rising CPI indicates increased inflation, which can influence interest rates and economic policies, while a declining CPI suggests deflationary trends. Because it encompasses a comprehensive range of goods and services, the CPI is particularly effective in showing how inflation affects consumers across different demographics, making it an essential tool for macroeconomic analysis.

Other options, while important in their contexts, do not serve as primary indicators for overall economic performance in the same way. The household savings rate and exchange rates provide relevant data but are more specific in scope, relating to individual financial behavior and international trade, respectively. Stock market performance can be a reflection of economic conditions but is often subject to speculation and may not accurately represent broader economic trends.